Answer:
the knee extensors must exert 15.87 N
Explanation:
Given the data in the question;
mass m = 4.5 kg
radius of gyration k = 23 cm = 0.23 m
angle ∅ = 30°
∝ = 1 rad/s²
distance of 3 cm from the axis of rotation at the knee r = 3 cm = 0.03 m
using the expression;
ζ = I∝
ζ = mk²∝
we substitute
ζ = 4.5 × (0.23)² × 1
ζ = 0.23805 N-m
so
from; ζ = rFsin∅
F = ζ / rsin∅
we substitute
F = 0.23805 / (0.03 × sin( 30 ° )
F = 0.23805 / (0.03 × 0.5)
F F = 0.23805 / 0.015
F = 15.87 N
Therefore, the knee extensors must exert 15.87 N
Answer:
Explanation:
spring constant of spring = mg / x
= .4 x 9.8 / ( .95 - .65 )
=13.07 N / m
energy stored in spring = 1/2 k x²
= .5 x 13.07 x ( 1.2 - .65 )²
= 1.976 J
Let it goes x m beyond its equilibrium position
Total energy at initial point
= 1.976 + 1/2 m v²
= 1.976 + .5 x .4 x 1.6²
= 2.488 J
energy at final point
= mgh + 1/2 k x²
.4 x 9.8 x ( .55 + x ) + .5 x 13.07 x² = 2.488
6.535 x² + 2.156 + 3.92 x = 2.488
6.535 x² + 3.92 x - .332 = 0
x = .075 m
7.5 cm
Answer:
4050 gallons
Explanation:
In first half and hour both pumps are working property . There for it give, 45
gallons per minute . Half and hour is equal to 30 minutes.After one pump was broken only one pump is working 30 minutes .
For 1st 30 minutes ,( 2 pumps are working )
Gallons = 45 * 30 *2 = 2700 gallons
2nd 30 minutes ( 1 pump is working )
Gallons = 45*30*1 = 1350 gallons
Total gallons = 2700+1350
= 4050 gallons
Answer:
T = 686.7N
Explanation:
For this exercise we will use Newton's second law in this case there is no acceleration,
∑ F = ma
T -W = 0
The gymnast's weight is
W = mg
We clear and calculate the tension
T = mg
T = 70 9.81
T = 686.7N
